Screened carbon trap protection

ABSTRACT

The present invention relates to a hydrocarbon trap positioned in the air intake system of a vehicle, upstream from the engine and wholly in the airflow. The hydrocarbon trap comprises a holder and a material for adsorbing the hydrocarbons, inserted inside the holder. The holder comprises a screen that is added at the end facing the engine. The screen is held in place with the help of a locking mechanism. The locking mechanism comprises a locking ramp on the holder and corresponding locking tab on a clamping ring surrounding the holder.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to U.S. Provisional PatentApplication Serial No. 60/355,312 filed Feb. 7, 2002.

TECHNICAL FIELD

[0002] The present invention relates generally to air intake systems andmore particularly to a hydrocarbon trap for adsorbing hydrocarbons inthe air intake systems.

BACKGROUND

[0003] Due to laws requiring the reduction of the levels of hydrocarbonsthat vehicles may emit into the atmosphere, it is necessary forautomotive designers to include systems in vehicles to measure andcontrol emissions. Hydrocarbons are released in a vehicle's exhaust, aswell as from the engine, even when it is not operating. Hydrocarbonsremaining from engine reactions can leak out of the engine through theengine's air intake.

[0004] The first step in reducing hydrocarbon emissions is to measurethe level of hydrocarbons present in the engine system. Many methodshave been utilized to measure the level of hydrocarbons in the exhaust.For example the hydrocarbon level in vehicle exhaust gas is measured byplacing a hydrocarbon adsorbing material in the exhaust stream of thevehicle. The hydrocarbon adsorbing material is connected to a sensor.The sensor is connected to an on-board diagnostic system that monitorsthe exhaust emissions and notifies the operator when the hydrocarbonlevel exceeds a certain level. However, this method does not reduce thehydrocarbon emissions by any significant amount.

[0005] Apart from measuring the level of hydrocarbons in the exhaust, itis thus beneficial reduce the level of hydrocarbons. One method of doingso is to absorb hydrocarbons from the exhaust flow via a filter-likedevice. A problem arises, however, wherein the adsorbing elementeventually becomes saturated with hydrocarbons and is no longer able tofunction effectively. It would be beneficial to have ahydrocarbon-trapping device that would not have this limitation. Such anelement could also be used to condition the air intake flow to increaseengine capacity as well as for implementing a hydrocarbon-measuringfeature.

[0006] Typically, the hydrocarbon-trapping device is formed of monolithcarbon that is disposed in the air induction system of motor vehicles.One of the problems with such positioning of the hydrocarbon-trappingdevice in the air induction system is the risk of breakage due tovibrations, or due to throttle engine backfire. In addition to the lossof function of the hydrocarbon-trapping device, large pieces of carbonmonolith may move towards the engine, thereby resulting in a prematurefailure of the engine of a motor vehicle.

[0007] Therefore, it is highly desirable to have a hydrocarbon-trappingdevice that substantially prevents carbon pieces from traveling to theengine. Additionally, it is also desirable to have ahydrocarbon-trapping device that enhances the hydrocarbon adsorbing.

SUMMARY

[0008] In one aspect of the present invention, a hydrocarbon trap isprovided capable of adsorbing and releasing hydrocarbons and ispositioned in the air intake system of a vehicle, upstream from theengine and wholly in the airflow.

[0009] In another aspect of the present invention, hydrocarbon trapcomprises a housing and hydrocarbon adsorbing material, inserted insidethe holder. A screen is added to the hydrocarbon trap such that in theevent of premature breakage of the hydrocarbon adsorbing material thecarbon particles do not flow towards the engine. In yet another aspectof the present invention, the hydrocarbon trap is provided with twoscreens.

[0010] In another aspect of the present invention, a hydrocarbon trapcomprises a housing defining a cylindrical body. A clamping ring isattachable to the body with the help of a locking mechanism.

[0011] In yet another aspect of the present invention, the hydrocarbontrap comprises a housing, an hydrocarbon adsorbing material and twoscreens for protecting the hydrocarbon adsorbing material from flowingto the engine. The housing is formed by joining two cylindrical bodies.The two screens are attached to the housing, such that one screen facesthe engine and the other away from the engine.

[0012] Other aspects and advantages of the present invention will becomeapparent upon considering the following detailed description andappended claims, and upon reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1 is a perspective view of a hydrocarbon trap device aspositioned in the air intake tube in accordance with the teachings ofthe present invention;

[0014]FIG. 2 is a perspective view of the hydrocarbon trap device ofFIG. 1 in accordance with the teachings of the present invention;

[0015]FIG. 3A is an end view of the hydrocarbon trap device of FIG. 1 inaccordance with the teachings of the present invention;

[0016]FIG. 3B is a cross sectional view along lines B-B in FIG. 3A inaccordance with the teachings of the present invention;

[0017]FIG. 4 is an alternate embodiment of the hydrocarbon trap deviceof FIG. 1 in accordance with the teachings of the present invention;

[0018]FIG. 5 is a perspective view of the third embodiment of thehydrocarbon trap device in accordance with the teachings of the presentinvention; and

[0019]FIG. 6 is a perspective view of the fourth embodiment of thehydrocarbon trap device in accordance with the teachings of the presentinvention.

DETAILED DESCRIPTION

[0020] Referring in particular to FIGS. 1 and 2, a hydrocarbon trap isgenerally shown and represented by reference numeral 10. The hydrocarbontrap 10, as the name suggests is able to adsorb and releasehydrocarbons.

[0021] Although not shown in the drawings the hydrocarbon trap 10 ispositioned in the air intake system (not shown) of a motor vehicle. Anair intake system is well known in the art and is not explained indetails. Preferably, the hydrocarbon trap 10 is positioned in the airintake tube 12 between the engine (not shown) and a dust filter (notshown). The preferred position of the hydrocarbon trap 10 is upstreamfrom the engine and wholly located in the airflow. When the engine isnot operating, hydrocarbons tend to leak out of the engine system andescape the vehicle thorough the air intake system. Therefore, thehydrocarbon trap 10 is preferably positioned in the air intake tube 12such that air must pass through the hydrocarbon trap 10 to escape theair intake tube 12 to the environment. When hydrocarbons are moving at aslow rate, such as when the engine is not pulling air into the airintake tube 12, the hydrocarbon trap 10 can adsorb the hydrocarbons

[0022] Referring in particular to FIGS. 2, 3A and 3B, hydrocarbon trap10 comprises a housing 14, a material 16 for adsorbing the hydrocarbonand a means 18 for preventing the material 16 from flowing to theengine.

[0023] The housing 14 includes a body 20 and ring 22. The ring 22extends outwards from the perimeter 24 of the body 20 of the housing 14.Preferably, the body 20 of the housing 14 has a cylindrical shape anddefines an interior surface 26 and an exterior surface 28. Preferably,the ring 22 is integral with the body 20 of the housing 14.Alternatively, the ring 22 may be attached to the body 20. A cylindricalshape for the body 20 of the housing 14 is preferred such that thehousing 14 can be easily inserted in the air intake flow tube 12.Alternatively, the holder 14 may have other shapes that will allow thehydrocarbon trap 10 to be placed in the air intake flow tube 12. Thehousing 14 is preferably made of a metallic material such as aluminum orsteel. Alternatively, the housing 14 may be made of plastic or othercomposite materials.

[0024] In order to explain the position of the housing 14 inside the airintake flow tube 12, an end of the body 20 housing 14 facing the dustfilter is referred to as a first face and is represented by referencenumeral 30. The end of the body 20 housing 14 facing the engine isreferred to as a second face and is represented by reference numeral 32.Although it can not be seen clearly in the drawings, the first face 30is open such that air passing through the air intake tube passes throughthe material 16. It must be understood that reference to first face 30and second face 32, is with reference to the dust filter and the engineand is in no way intended to limit the invention. As clearly shown inFIG. 2, the ring 22 is formed on the second face 32 of the housing 14.In other words, the ring 22 faces the engines when the housing 14 ispositioned inside the air intake flow tube 12.

[0025] With continued reference to FIGS. 2, 3A and 3B, the material 16adsorbs the hydrocarbons released by the engine when the engine is notoperating and release these hydrocarbons when the engine is operating.As shown, the material 16 is inserted inside the interior surface 26 ofthe body 20 of the housing 14 by a positive step. In order toefficiently adsorb hydrocarbons, the material 16 is entirely formed fromcarbon. Preferably and as shown in FIG. 2, the material 16 is a carbonmonolith having a honeycomb structure. The honeycomb construction of thematerial 16 will allow air to pass through the material 16 when theengine is turned on and release hydrocarbons into the engine.Alternatively, the material 16 could be constructed from carbon mixedwith a binder material such as gray clay or ceramic. As clearly shown inFIG. 3B, in order to prevent the material 16 from any substantial damagedue to harsh environment, the interior surface 26 of the body 20 of thehousing 14 is provided with a cushion ring 34. The cushion ring 34surrounds the material 16 and is preferably formed of a urethane or afoam material.

[0026] The preferred embodiment of the material 16 is alsoself-regenerating. Rather than adsorbing hydrocarbons and trapping themin until the material 16 is saturated, the hydrocarbons may berelatively easily released from the hydrocarbon trap 10. The releaseoccurs when the engine is operating and pulling air into the air intaketube 12 at a moderate to high rate. Preferably, when air passes thoughthe hydrocarbon trap 10 at a moderate to high rate, the hydrocarbonstrapped in the material 16 are pulled out and travel down the air intaketube 12 to the engine, where they are burned off. By allowing thehydrocarbons to be released from the material 16, the preferredembodiment of the invention is self-regenerating, and the material 16does not have to be replaced over the lifetime of the vehicle as aresult of hydrocarbon build-up.

[0027] With continued reference to FIGS. 2, 3A and 3B, the hydrocarbontrap 10 is also provided with a means 18 such as a screen for preventingthe material 16 from flowing to the engine, in situations where there ispremature breakage of the housing 14. Preferably, the screen 18 isattached on the second face 26 of the housing 14. Alternatively, asshown in FIG. 4, the screen 18 may be attached on both the first face 30and the second face 32 of the body 20 of the housing 14.

[0028] As clearly shown in FIG. 3A, the screen 18 has a spherical shapesuch that it can be placed against the perimeter 24 of the body 20 ofthe housing 14. As shown in FIG. 3A, the screen 18 defines chambers ortiny holes 36 to allow air and hydrocarbons to pass through the screen18. However, the size of the holes 36 in the screen 18 is such that theywill prevent any large pieces of material 16 from flowing towards theengine. Preferably, the screen 18 is formed of steel wires.Alternatively, the screen 18 may be made of other materials such asplastic. As clearly shown in FIG. 3A, the screen 18 is attached to thehousing 14 by welding the screen 18 against the perimeter 24 of the body20 of the housing 14. Traditional welding methods such as heat staking,laser welding etc. may be used to attach the screen 18 to the housing14.

[0029]FIG. 5 represents an alternate embodiment of the hydrocarbon trapshown and described in FIG. 2. Like the hydrocarbon trap of the firstembodiment, the hydrocarbon trap 100 comprises a housing 114, a material116 for adsorbing hydrocarbon and a means 118 for preventing thematerial 116 from flowing to the engine. The housing 114 is formed of abody 120 with a clamping ring 122 clamped around the perimeter 124 ofthe cylindrical body 120. Like the first embodiment, the body 120 of thehousing 114 is cylindrical in shape such that it can be positionedinside an air intake tube. The cylindrical body 120 defines an exteriorsurface 126 and an interior surface 128. Preferably, the clamping ringis formed of the same material as the body 120 of the housing 114.Alternatively, it may be formed of a different material.

[0030] In order to attach the clamping ring 122 to the body 120 of thehousing, the clamping ring 122 defines an outwardly extending flange130. As shown in FIG. 5, the outwardly extending flange 130 has a largerdiameter than the diameter of the body 120 such that it fits partiallyover the body 120. The flange 130 has at least one locking device 134extending from the flange 130. The body 120 of the housing is providedwith a corresponding locking ramp 136. As clearly shown in FIG. 5, thelocking device 134 and the locking ramp 136 are snap fitted togethersuch that a the clamping ring 122 is tightly clamped around the exteriorsurface 126 of the body 120. Preferably, the locking ramp 136 isnon-planar and defines a non-flat profile seat. The screen 118 is placedagainst the perimeter 124 of the body 120 and is held in place betweenthe locking ramp 136 and the locking device 134. The clamping ring 122is tightened around body 120 of the housing 114 with the help offasteners or by welding/heat staking. Additionally, as shown in the FIG.5 the exterior surface 126 of the body 120 may define a heat stakedrivet 138 that will hold the clamping ring 122 to the body 120 of thehousing 114. The heat staked rivet 138 will prevent any prematuredetachment of the clamping ring 122 from the body 120. As seen fromabove, this arrangement imparts radial strength to the screen 118 suchthat the collapse strength of the hydrocarbon trap 100 is enhanced.

[0031]FIG. 6 represents a third embodiment of the hydrocarbon trap 10shown in FIG. 2. As shown in the FIG. 6 the hydrocarbon trap 200comprises two cylindrical housings 210 and 212. Like the firstembodiment, the hydrocarbon trap 200 comprises a material 214 foradsorbing hydrocarbons. Each housing 210, 212 defines an interiorsurface 216 and an exterior surface 218. The housings 210 and 212 areprovided with screens 220 and 222. As clearly seen in FIG. 6, one screen220 faces the dust filter and the other screen 222 faces the engine. Thematerial 214 is inserted into the interior surface 216 of the housings210 and 212, such that the material 214 is between the screen 114 and116. Preferably, the screens are attached to the housing by the methoddescribed in the first embodiment. Alternatively, the locking mechanismdescribed in the third embodiment may be used to attach the screen 220and 222 to the housing 210 and 212. The two cylindrical holders 210 and212 are attached to each other with the help of fasteners oralternatively by spin welding them together.

[0032] As seen from the above, the present invention provides for ahydrocarbon trap that is more stable and substantially prevents largepieces of carbon from traveling to the engine. Secondly, the hydrocarbontrap of the present invention also provides for adsorption ofhydrocarbons when the engine is not running, thereby reducing the amountof hydrocarbons released in into the atmosphere.

[0033] While the invention has been described in terms of preferredembodiments, it will be understood, of course, that the invention is notlimited thereto since modifications may be made by those skilled in theart, particularly in light of the foregoing teachings.

What is claimed is:
 1. A hydrocarbon trapping device positioned in theair intake system of an engine, wherein the device is placed upstreamfrom the engine, the device comprising: a housing having a body, whereinone end of the body faces the engine and the other end away from theengine;; an element housed in the body of the housing, for adsorbinghydrocarbons released by the engine; and a screen for preventing theelement from flowing to the engine.
 2. The device of claim 1, whereinthe body is cylindrical.
 3. The device of claim 1, wherein the elementhas a plurality of chambers define therein, the chambers arranged so asto allow air to pass through the element.
 4. The device of claim 2,wherein the chambers are arranged in a honeycomb pattern.
 5. The deviceof claim 1, wherein the element is a carbon element.
 6. The device ofclaim 1, wherein the screen is welded to the body of the housing at theend facing the engine.
 7. The device of claim 1, wherein the screen is awire mesh screen.
 8. The device of claim 7, wherein the wire mesh screencomprises plurality of holes to allow air to pass through, wherein theplurality of holes are smaller than the plurality of chambers in theelement.
 9. The device of claim 1, wherein the screen is made of amaterial consisting of aluminum, steel and plastic.
 10. The device ofclaim 1, wherein the housing further comprises a clamping ringattachable around a perimeter of the body of the housing.
 11. The deviceof claim 10, wherein clamping ring is attachable to the body by alocking mechanism.
 12. The device of claim 11, wherein the lockingmechanism comprises a locking tab on the clamping ring and a lockingramp on the body, such that the locking tab snap fits into the lockingramp.
 13. The device of claim 10, wherein the screen is inserted betweenthe end of the clamping ring and the end of the body facing the engine.14. the device of claim 1, further comprising a second screen attachableto the end away from the engine.
 15. A hydrocarbon trapping devicepositioned in an air intake system of an engine, wherein the device ispositioned upstream from the engine, the device comprising: a housing,wherein the housing defines a first face facing the engine, and a secondface away from the engine; an element for adsorbing hydrocarbons,wherein the housing houses the element between the first face and thesecond face; a first screen attachable to the first face of the housing;and a second screen attachable to the second face of the housing. 16.The device of claim 15, wherein the housing is formed of two cylindricalbodies having a hollow interior.
 17. The device of claim 15, wherein theelement has a plurality of chambers define therein, the chambersarranged so as to allow air to pass through the element.
 18. The deviceof claim 17, wherein the chambers are arranged in a honeycomb pattern.19. The device of claim 17, wherein the element is a carbon element. 20.The device of claim 15, wherein the first screen and the second screenare welded to the first face and the second face.
 21. The device ofclaim 15, wherein the first screen and the second screen are made of amaterial consisting of aluminum, steel and plastic.